Wireless power utilization in a local computing environment

ABSTRACT

Various embodiments of a wirelessly powered local computing environment are described. The wireless powered local computing environment includes at least a near field magnetic resonance (NFMR) power supply arranged to wirelessly provide power to any of a number of suitably configured devices. In the described embodiments, the devices arranged to receive power wirelessly from the NFMR power supply must be located in a region known as the near field that extends no further than a distance D of a few times a characteristic size of the NFMR power supply transmission device. Typically, the distance D can be on the order of 1 meter or so.

TECHNICAL FIELD

The described embodiments relate generally to utilizing a wireless powertransmission in a portable computing environment.

BACKGROUND

It has been discovered (see “Efficient wireless non-radiative mid-rangeenergy transfer” by Karalis et al., Annals of Physics 323 (2008) pgs.34-38) that useable power can be transferred wirelessly from a powersource to a receiver located within a distance referred to as a nearfield. With wireless power transmission there is a need for apparatusesand methods for transmitting and relaying wireless power at varyingpower levels and multiplexed times to increase power transmissionefficiency.

SUMMARY

The present invention provides a system and method for utilizingwireless near field magnetic resonance (NFMR) power transmission in acomputing environment.

In various embodiments, methods, systems, and apparatus for interactingbetween a plurality of peripheral devices receiving power wirelesslyfrom a wireless power supply is described. In one embodiment, a virtualcharging area can be created. The virtual charging area can extend toabout about one (1) meter from a central station that incorporates aNFMR power supply. The virtual charging area can define a region inwhich suitably configured peripheral devices, such as a mouse, keyboard,and so on can receive power by way of a NFMR channel formed between theNFMR power supply and a NFMR resonator circuit included in theperipheral device. In this way, when both the NFMR power supply and theNFMR resonator circuit are tuned to each other, then useable power canbe transferred over a power conduction channel formed between the tworesonant devices.

In some embodiments, at least one of the peripheral devices can have atunable resonator circuit having at least one circuit element (such as aresistor, inductor, or capacitor) having a value that can be changed. Inthis way, the tunable resonator circuit can be de-coupled from the NFMRpower supply by de-tuning the tunable resonator circuit in relation tothe resonance frequency of the NFMR power supply. In this way, theeffective Q value of the tunable circuit is reduced to the point thatessentially no power is transferred. In one embodiment, at least one ofthe plurality of peripheral devices can include a secondary NFMRresonator circuit adapted to re-resonant power to another one of theplurality of peripheral devices by establishing a NFMR channel to theother peripheral device over which useable power can be transferred. Insome embodiments, the NFMR power supply can eliminate any voids in thevirtual charging area by modifying resonance characteristics such asfrequency.

A method of wirelessly transmitting power can be performed by creating afirst coupling mode region of an electromagnetic field within a nearfield of a power supply transmit antenna, coupling the electromagneticfield and a receiver antenna of a first receiver device within thecoupling mode region, creating a second coupling mode region of theelectromagnetic field different from the first coupling mode regionwithin a near field of a transmit antenna of the first receiver device,coupling the electromagnetic field to a receive antenna of secondreceiver device in the near field of the transmit antenna of the firstreceiver device, wirelessly delivering power from the power supply tothe first receiver device by way of the power supply transmit antennausing the first coupling mode region of the electromagnetic field; andwirelessly delivering at least some of the power wirelessly delivered tothe first receiver device is wirelessly by re-transmitting the at leastsome power to the second receiver device by way of the first receivertransmit antenna using the second coupling mode region of theelectromagnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS

The included drawings are for illustrative purposes and serve only toprovide examples of possible structures and arrangements for thedisclosed embodiments. These drawings in no way limit any changes inform and detail that may be made to the described embodiments by oneskilled in the art without departing from the spirit and scope of theembodiments.

FIG. 1 illustrates representative tunable resonator circuits inaccordance with the described embodiments.

FIG. 2 shows representative virtual charging area in accordance with thedescribed embodiments.

FIG. 3 shows representative hybrid power circuit in accordance with thedescribed embodiments.

FIG. 4 shows representative time multiplexing for distributing power inaccordance with the described embodiments.

FIG. 5 illustrates a wireless transmission system.

FIG. 6 shows a simplified schematic diagram of a wireless power transfersystem.

FIG. 7 shows an exemplary antenna.

FIG. 8 shows a flowchart detailing process 800 in accordance with thedescribed embodiments.

DETAILED DESCRIPTION

Various embodiments of a wirelessly powered local computing environmentare described. The wireless powered local computing environment includesat least a near field magnetic resonance (NFMR) power supply arranged towirelessly provide power to any of a number of suitably configureddevices. In the described embodiments, the devices arranged to receivepower wirelessly from the NFMR power supply can be located in a regionknown as the near field that extends no further than a distance D thatcan be a few times a characteristic size of the NFMR power supplytransmission device. Typically, the distance D can be on the order of 1meter or so.

FIG. 1 shows various representative tunable circuits in accordance withthe described embodiments. The representative tunable circuits caninclude series RLC (resistor (R), inductor (L), capacitor (C)) circuit102. In this arrangement, a resonant frequency can be tuned (i.e.,changed) by changing any of the component values. For example, circuit102, capacitor C can be a variable capacitor used to tune circuit 102.Similarly, circuit 104 (known as a Hartlely oscillator) can be used as atunable circuit in the described embodiments as can tuned LC circuit106.

FIG. 2 shows representative virtual charging area 200 in accordance withthe described embodiments. Virtual charging area 200 provides region Rof charging for suitably configured devices placed within the region R.NFMR power supply can be placed in central unit such as desktopcomputer. In this way, the desktop computer can provide the NFMR powersupply with computing resources. It should be noted that the near fieldmagnetic resonance (NFMR) power supply can include high Q circuit thatrelies upon near field magnetic coupling by way of a resonance channelformed between resonances of the power source and sink to transferpower. The NFMR power supply can be a standalone unit such as, forexample, included in a desk top computer, laptop computer, tabletcomputer, and so on. In other embodiments, the NFMR power supply cantake the form of a portable type unit such as a dongle that can beconnected to a legacy device such as a desktop computer therebyproviding the ability to retrofit devices. In still other embodiments,housing or a portion of a housing used to enclose the NFMR power sourcecan act to extend a useful range of the NFMR power supply.

In this way, suitably configured peripheral devices can be powereddirectly from the NFMR power supply. In so doing, the peripheral deviceswhen tuned to the appropriate frequency can receive power wirelesslyfrom the NFMR power supply. In so doing, the appropriately tunedperipheral device can be considered to be part of a resonance circuitthat can include the NFMR power supply and any other peripheral devicesso tuned. As part of such a circuit, each device has associated with ita corresponding load that can be sensed by the NFMR power supply. Assuch, the resonance circuit can have a characteristic load that canchange by the addition or deletion of devices from the resonancecircuit. For example, if a suitably configured device such as a portablemedia player is brought within range of the NFMR power supply, then theload associated with the portable media player can be sensed by the NFMRpower supply when (and if) the portable media player is appropriatelytuned. It should be noted that in some cases, the device being broughtinto the range of the NFMR power supply can communicate its initialpresence using a standard communication protocol such as WiFi orBluetooth. However, once incorporated into the resonance circuit, thedevice can use a communication back channel described in detail below.Accordingly, any change in the characteristic load factor of theresonance circuit can convey information that can be used by the NFMRpower supply to control the various devices in the resonance circuit by,for example, distributing power, and so on.

In some embodiments, certain of the peripheral devices can be configuredto include a re-resonator circuit that can receive power directly fromthe NFMR power supply. Such devices can also transfer a portion of thepower received to other of the peripheral devices. For example, as shownin FIG. 2 virtual charging area 200 includes central unit 202 (desktopcomputer) that can include the NFMR power supply, keyboard 204, mouse206, and portable media player 208. In one embodiment, keyboard 204 canbe configured to receive power directly from the NFMR power supplyincluded in desktop computer 202 as can mouse 206 and portable mediaplayer 208 (when located within range R).

In some cases, the ability of desktop computer 202 to provide powerdirectly to mouse 206, for example, can be reduced due to any number offactors. Such factors can include, for example, the addition of otherdevices into region R that require power from the NFMR power supply,obstacles interfering with the direct power channel formed between theNFMR and mouse 206, and so on. In this case, keyboard 204 can act as are-resonator such that a portion of the power delivered to keyboard 204from the NFMR power supply can be passed on by way of a re-resonatortransmission unit (not shown) in keyboard 204. In this way, any powerloss experienced by mouse 206 can be ameliorated by the power receivedfrom keyboard 204. This arrangement can be transitory or can last for aslong as mouse 206 is not able to receive adequate power directly fromthe NFMR power supply. In other cases, the locating of portable mediaplayer 208 within region R can reduce the amount of power available tokeyboard 204 and mouse 206. In this case, if a battery in keyboard 206is fully charged (or additional charge is not necessary) then keyboard206 can decouple a charging circuit while still maintaining are-resonator circuit providing power to mouse 206.

In some embodiments, dongle 210 can be connected to desktop computer 202(by way of a USB port or cable, for example). So connected, dongle 210can, in turn, act as a range extender for the NFMR power supply. In thisway, dongle 210 can extend a range that power can be provided by theNFMR power supply included in desktop computer 202. In some cases,dongle 210 can re-resonate power already received from the NFMR powersupply while in other cases, dongle 210 can include its own NFMR powersupply. By having its own NFMR power supply, dongle 210 can provideadditional power wirelessly to those devices within virtual chargingregion 200 separate from the power provided by the NFMR power supplyincluded in desktop 202. It should be noted that in some embodiments,the housing of desktop computer 202 (or a portion thereof) can be usedas a resonator as part of the NFMR power supply.

FIG. 3 shows representative hybrid power circuit 300 in accordance withthe described embodiments. As described, hybrid power circuit 300 canmatch the low power delivery capability of the NFMR power supply to alarge power requirement of required for long term storage devices, suchas lithium ion polymer (LiPO) battery. Batteries in such devices asportable phones, portable media players, and so on, can requirerelatively large amount of power to charge that can be greater than thatavailable from the NFMR power supply. Therefore, it is difficult tocharge these high capacity batteries such as LiPO using the NFMR powersupply. However, a short term charge storage device (such as acapacitor, ultra capacitor, and so on) that can be charged up by powerdelivered by the NFMR power supply can be used to temporarily storecharge prior to being passed to the battery. In this way, oncesufficient charge is stored in the short term charge storage device, thestored charge can be used to charge a long term charge storage device(such as a LiPO battery). For example, FIG. 3 shows representativehybrid power circuit 300 having capacitor 302, capacitor chargingcircuit 304 (that can receive power P from the NFMR power supply), longterm power storage unit 306 (that can take the form of battery 306), andbattery charging circuit 308. In the described embodiment, power Pprovided by the NFMR power supply can “trickle” charge capacitor 302.Once sufficient charge is stored in capacitor 302, capacitor chargingcircuit 304 can sense capacitor voltage VC and switch fully chargedcapacitor 302 to battery 306 by way of battery charging circuit 308. Inthis way, charge Q stored in capacitor 302 can be used to increase thecharge of battery 306. Once capacitor 302 is discharged (as determinedby capacitor charging circuit 304), capacitor 302 can again receivepower P from the NFMR power supply.

One of the advantages of a wirelessly powered local computingenvironment is the potential to provide an enhanced user experience. Forexample, by doing away with clumsy and annoying cables and eliminatingthe need to replace batteries, an easy to use and efficient localcomputing environment can be provided to the user. However, in order toprovide this enhanced user experience, it would be advantageous for thevarious devices that make up the wirelessly powered local computingenvironment to be able to interact with each other as well as with theNFMR power supply. Such interaction can include, for example, providingpower by the NFMR power supply to any of the devices within range inwhatever amount is required. For example, an amount of power transferredbetween the NFMR power supply (having a first resonator circuit) andreceiving device (having a second resonator circuit) can be controlledby tuning (or de-tuning) the second resonator circuit along the linesdescribed above. It should be noted that when a device is tuned, thetuned device can become part of the resonance circuit. As part of theresonance circuit, a load associated with the device can be “seen” bythe NFMR power supply. This load can, in turn, be used by the NFMR powersupply to determine the power requirements of the resonance circuit aswell as how the required power must be distributed amongst the variousdevices included in the resonance circuit. On the other hand, when adevice “de-tunes”, then the device no longer resonates with the NFMRpower supply and is effectively removed from the resonance circuit andreceives little or no additional power.

It should be noted that various environmental factors can have an effecton the efficiency of power transfer from the NFMR power supply to thosedevices included in the resonance circuit. For example, any object(metallic, for example) that can interfere with the magnetic couplingbetween the NFMR power supply and those device wirelessly receivingpower can adversely affect both the amount of power supplied and theefficiency of the power transfer. This reduction in power transferred orpower transfer efficiency can put an undue strain on the NFMR powersupply as well as increase the likelihood that particular devices maynot have sufficient power to operate at peak efficiency, to executeimportant functions, or in some cases, not be able to operate at all. Inone embodiment, feedback provided by a device to the NFMR power supplyindicating that the device requires more power or has experienced areduction in power can cause the NFMR power supply to try to ascertainthe reason or reasons why the device has experienced this reduction inpower. For example, if the device is moving within a void region (a voidbeing defined as that region having a substantially reduced powertransmission or efficiency factor), then the NFMR power supply canattempt to move the void region by modifying selected resonance factors(such as resonance frequency) thereby having the effect of moving thevoid region (hopefully beyond the range of the operating region of thedevices wirelessly coupled to the NFMR power supply). In one embodiment,the NFMR power supply can determine that the power transfer efficiencyhas dropped below a threshold for a device(s) based upon, for example,feedback from the affected device(s). In response, the NFMR power supplycan respond by modifying the frequency of the magnetic resonance signaluntil the power efficiency has recovered to above the threshold, byincreasing power, or by, in some cases, causing less important or lessused devices, to de-tune themselves (thereby removing themselves fromthe resonance circuit) so as to free up power that can be provided tothose devices requiring more power. It should be noted that theseoperations can be carried out in the background in such a way that theuser is unaware of the operations taking place. In still anotherembodiment, the power source can alter phase, frequency and or signalamplitude relative to other links in order to optimize power delivery.

In order to provide more robust communication between the variousdevices coupled with the NFMR power supply, each device can provideaffirmative feedback to the NFMR power supply using a directcommunication channel such as Bluetooth or WiFi. It should be noted,however, that an indirect communication channel can also be used. Suchan indirect communication channel can be formed using the resonancecircuit load factor mediated by the number (and type) of deviceswirelessly coupled with the NFMR power supply. Since each device has anassociated resonance load (i.e., load perceived by the NFMR power supplywhen a device is tuned to the proper resonance frequency), an indirectcommunication channel mediated by load state of the device, or devicesin the resonance circuit can be established with the NFMR power supply.For example, the NFMR power supply can characterize a particular loadstate of a resonance circuit by ascertaining the overall resonance load(i.e., sense load on resonant circuit). Any changes to the load statecan indicate a change in the status of the resonance circuit which, inturn, can infer that one or more of the devices previously included inthe resonance circuit (i.e., tuned to the NFMR power supply resonantfrequency) has dropped out, or de-tuned. In some cases, a Morse codelike communication protocol can be established between the NFMR powersupply and each of the devices. This Morse code like communicationprotocol can be based upon a device tuning and de-tuning itself using anidentifiable pattern. In this way, a simple device identifier, forexample, can be communicated to the NFMR power supply. Using thisarrangement, a device that has determined to de-tune itself and toremove itself from the resonance circuit, can signal the NFMR powersupply its intent as well as identify itself. In this way, the NFMRpower supply can have a more clear understanding of the condition of theresonance circuit and the devices included therein. This device todevice communication channel (also referred to as a back channel) can becapable of communicating simple information. Such information caninclude, for example, a device identifier, a synchronization flag, andso on. It should be noted that this communication channel is independentand separate from other communication channels provided by, for example,WiFi or Bluetooth.

For example, if keyboard is using power wirelessly provide by the NFMRpower supply to charge its battery, when the keyboard determines thatthe battery is substantially fully charged, then the keyboard candetermine that power from the NFMR power supply is no longer required(at least until the battery discharges to a pre-set level). In thiscase, the keyboard can notify the NFMR power supply that it no longerrequires power (or at least until it signals that it requires power atsome future point in time). In this case, the NFMR can redirect poweraway from the keyboard (using, for example, a different resonantfrequency when the NFMR power supply is equipped to transmit power on anumber of frequency ranges, or bands) or the keyboard can remove itselffrom the resonance circuit (either on its own or as directed) byde-tuning itself. In this way, the load of the resonance circuit can bereduced allowing more power to be wirelessly delivered to the otherdevices in the resonance circuit. It should be noted that for efficiencyand environmental reasons, the NFMR power supply will provide only asmuch power as is needed. For example, as battery charges up then lesspower is required. In this way, the charge state of the battery can becommunicated to the NFMR power supply that can respond by reducing, orthrottling back, the power provided to the keyboard.

It should be noted that while a device can be removed from the resonancecircuit by the process of de-tuning, the device can be added to theresonance circuit by tuning it. By tuning (and conversely de-tuning) itis meant that circuit characteristics (such as resistance) can bechanged resulting in the circuit Q increasing in the case of tuning ordecreasing in the case of de-tuning. It should be noted that therelative increase or decrease in Q for a circuit can be dependent uponthe circuit and applications to which the circuit is used.

When a device is brought within range R of the power supply, then theload experienced by the power supply increases by that amountcorresponding to the device. In this way, proximity detection can bethought as having taken place that can trigger an action to be taken.For example, if a portable media player is brought within range R of adesktop computer, then the proximity signal generated by the change inload experienced by the power supply can cause the desktop computer toinitiate a synchronization process, for example, between the portablemedia player and the desktop computer.

The communication channels established between the various devices inthe resonance circuit can be used for the devices to determine amongstthemselves which device takes priority with regards to power supplied bythe NFMR power supply. In other cases, a host device (that includes theNFMR power supply and any associated computing resources) can act asaggregator. By aggregator, it is meant that the host device candetermine the priority of those devices for receiving power, how muchpower to receive, and for how long. It should be noted that some devicesand or some operations performed by a device can have a higher prioritythan other devices and or operations. For example, a high prioritydevice(s) may require guaranteed power for operation (such as using amouse vs charging a portable media player). The host device can use anysuitable priority mechanism (round robin, for example).

In another embodiment, the devices receiving power can communicateamongst themselves to determine which device has priority. The devicesunderstand their own operating points, such as a minimum amount of powerto perform certain function, maximum power required to perform allfunctions. In this way, each device can provide a desired amount ofpower, a list of functions that can be performed, and a minimum amountof power required for operation. The source can determine how much powercan be delivered and which device can get the power it needs. In somecases, the devices themselves set the priority, in other cases, the hostdevice sets the priority. When a device is not receiving power, itremoves itself from the resonance circuit by de-tuning, and returns tothe circuit by re-tuning.

It should be noted that the NFMR power supply can use any number ofprotocols to wirelessly provide power to the various devices included inthe resonance circuit. For example, the NFMR power supply can include aplurality of resonator circuits each arranged to resonate at aparticular frequency. In this way, the NFMR power supply can providepower orthogonally using different frequency bands. In this way, adevice can have multiple resonant frequencies in order to take advantageof the frequency bands provided by the NFMR power supply. For example,the NFMR power supply can wirelessly provide power using multiplefrequency bands where a number of devices can each tune themselves to aparticular frequency. In this way, frequency shifting techniques can beused to more efficiently transfer power to the plurality of deviceswithin range of the NFMR power supply.

Other mechanisms for a single NFMR power supply to independentlytransmit power to more than one device includes time multiplexing asshown in FIG. 4. As illustrated, devices 400, 402 and 404 can each taketurns tuning and de-tuning themselves such that at any one time only oneof the devices if receiving power. For example, during a period 1,device 400 receives power by tuning itself to at least one of theavailable resonant frequencies while devices 402 and 404 are de-tuned.Once device 400 has completed its power cycle, device 400 de-tunesitself and device 402 tunes itself and receives power wirelessly fromthe NFMR power supply. Once device 402 completes its power cycle, device402 de-tunes itself and device 404 tunes itself to at least one of theresonance frequencies to receive power from the NFMR power supply. Inother embodiments, the NFMR power supply can use frequency multiplexingin which the NFMR can toggle amongst a number of frequencies each onetuned to a particular device. The device can receive power only when thedevice resonates with a current frequency of the power supply.

The closed loop control can also affect the modes of operation of thedevices in the resonance circuit. For example, a keyboard can determinean amount of power received from the source which will depend upon thedistance between the source and the keyboard (as well as the presence ofany interfering objects). If the power received falls below a threshold,then the keyboard can use more battery power or request that the sourceincrease power. In some cases, if the power provided can not beincreased to meet the current operating requirements of the keyboard,then the keyboard can take action to reduce its power requirements by,for example, reducing backlight, etc. It should be noted that asdiscussed above, the reduction on power received by the keyboard can becaused by many other factors other than an increase in distance. Suchfactors can include, for example, the presence of voids, objects, otherdevices added to the circuit, and so on.

FIG. 5 illustrates a wireless transmission system 500. Input power 502is provided to a transmitter 504 for generating a magnetic field 506 forproviding energy transfer to receiver 508 that generates an output power510 where the transmitter 504 and the receiver 508 are separated by adistance 512. When the frequency of receiver 508 and the frequency oftransmitter 504 are resonant, transmission losses between thetransmitter 504 and the receiver 508 are minimal.

An efficient energy transfer occurs by coupling a large portion of theenergy in the near-field of the transmitter 504 antenna to the receiver508 antenna rather than propagating most of the energy in anelectromagnetic wave to the far field. The area around the transmitterantenna 514 and receiver antenna 518 with this near-field coupling isreferred to as a coupling-mode region.

FIG. 6 shows a simplified schematic diagram of a wireless power transfersystem that includes transmitter 504 having an oscillator 622 thatgenerates a desired frequency varied by signal 623, a power amplifier624 and a filter and matching circuit 626 and responsive to controlsignal 625. The filter and matching circuit 626 can be included tofilter out harmonics or other unwanted frequencies and match theimpedance of the transmitter 504 to the transmit receiver antenna 514.

The receiver 508 can include a matching circuit 632 and a rectifier andswitching circuit 634 to generate a DC power output in response tosignal 635 to charge a battery 636 as shown in FIG. 6 or power a devicecoupled to the receiver 508 (not shown). The matching circuit 632 can beincluded to match the impedance of the receiver 508 to the receiveantenna 518. The receiver 508 and transmitter 504 can communicate on aseparate communication channel 619 (e.g., Bluetooth, cellular, etc).

FIG. 7 shows antenna 750. The resonant frequency of antenna 750 is basedon inductance and capacitance. Inductance in antenna 750 is generallythe inductance created by the antenna, whereas, capacitance is generallyadded to the inductance of antenna 750 to create a resonant circuit at adesired resonant frequency. For example, capacitor 752 and capacitor 754can be added to antenna 750 to create a resonant circuit that generatesresonant signal 756.

FIG. 8 shows a flowchart detailing process 800 in accordance with thedescribed embodiments. Process 800 can begin at 802 by creating a firstcoupling mode region of an electromagnetic field within a near field ofa power supply transmit antenna. Next at 804, the electromagnetic fieldand a receiver antenna of a first receiver device are coupled with thecoupling mode region. At 806, a second coupling mode region of theelectromagnetic field different from the first coupling mode region iscreated with a near field of a transmit antenna of the first receiverdevice. At 808, the electromagnetic field is coupled to a receiveantenna of second receiver device in the near field of the transmitantenna of the first receiver device. At 810, power is wirelesslydelivered from the power supply to the first receiver device by way ofthe power supply transmit antenna using the first coupling mode regionof the electromagnetic field. At 812, at least some of the powerwirelessly delivered to the first receiver device is wirelesslyre-transmitted to the second receiver device by way of the firstreceiver transmit antenna using the second coupling mode region of theelectromagnetic field.

What is claimed is:
 1. A method of wirelessly transmitting power,comprising: at a wireless power supply: coupling a first electromagneticfield of the wireless power supply and a first device; coupling a secondelectromagnetic field to a second device, wherein the first device iscommunicatively coupled to the second device; causing a resonant circuitof the first device to tune and detune to at least one of multiplefrequency bands of the wireless power supply; receiving load states fromthe first device and the second device; wirelessly distributing power tothe first device and the second device in accordance with the loadstates, wherein at least a portion of the power received by the firstdevice is wirelessly provided to the second device; and when an updatedload state is communicated between the first device and the seconddevice: causing a wireless redistribution of the power between the firstdevice and the second device based on the updated load state.
 2. Themethod as recited in claim 1, the method further comprising: receivingan initial communication from the first device via a wireless networkingprotocol for indicating a presence of the first device to the wirelesspower supply.
 3. The method as recited in claim 1, further comprising:establishing a communication channel between the first device and thesecond device based on the load states.
 4. The method as recited inclaim 3, wherein establishing the communication channel between thefirst device and the second device comprises determining a code patternbased on tuning and detuning between the first device and the seconddevice.
 5. A computing device, comprising: a processor; and a memorystoring instructions that when executed by the processor cause thecomputing device to perform steps that include: coupling a firstelectromagnetic field of the computing device to a first device;coupling a second electromagnetic field of the computing device to asecond device, wherein the first device is communicatively coupled tothe second device; causing a resonant circuit of the first device totune and detune to at least one of multiple frequency bands of thecomputing device; receiving load states from the first device and thesecond device; wirelessly distributing power to the first device and thesecond device in accordance with the load states, wherein at least aportion of the power received by the first device is wirelessly providedto the second device; and when an updated load state is communicatedbetween the first device and the second device: causing a wirelessredistribution of the power between the first device and the seconddevice based on the updated load state.
 6. The computing device asrecited in claim 5, wherein the steps further include: receiving aninitial communication from the first device via a wireless networkingprotocol for indicating a presence of the first device to the computingdevice.
 7. The computing device as recited in claim 5, wherein the stepsfurther include: establishing a communication channel between the firstdevice and the second device based on the load states.
 8. The computingdevice as recited in claim 7, wherein establishing the communicationchannel between the first device and the second device comprisesdetermining a code pattern based on tuning and detuning between resonantcircuits of the first device and the second device.
 9. An apparatus,comprising: a resonant circuit; a processor; and a memory storinginstructions that when executed by the processor cause the apparatus toperform steps that include: coupling a first electromagnetic field of afirst device and the apparatus; communicatively coupling to a seconddevice, wherein the second device is coupled to the first device via asecond electromagnetic field; causing the resonant circuit of theapparatus to tune and detune to at least one of multiple frequency bandsof the first device; providing a load state to the first device;receiving, based on the load state, wireless power from the firstdevice; providing wireless power to the second device; and when anupdated load state is received from the second device: causing awireless redistribution of the power between the apparatus and thesecond device based on the updated load state.
 10. The apparatus asrecited in claim 9, wherein the steps include: establishing acommunication channel between the apparatus and the second device bydetermining a code pattern, wherein the code pattern is based on tuningand detuning between resonant circuits of the apparatus and the seconddevice.
 11. The apparatus as recited in claim 9, wherein the stepsfurther include: providing feedback to the first device indicating thata power transfer efficiency has dropped below a threshold.
 12. A methodof wirelessly transmitting power, comprising: at a wireless powersupply: coupling a first electromagnetic field to a first device;coupling a second electromagnetic field to a second device, wherein thefirst device is communicatively coupled to the second device; receivingload states from the first device and the second device; wirelesslydistributing power to the first device and the second device inaccordance with the load states, wherein at least a portion of the powerreceived by the first device is wirelessly provided to the seconddevice; receiving an indication that a power transfer efficiency hasdropped below a threshold for at least the first device or the seconddevice; and when an updated load state is communicated between the firstdevice and the second device: causing a wireless redistribution of thepower between the first device and the second device based on theupdated load state.
 13. The method as recited in claim 12, furthercomprising: establishing a communication channel between the firstdevice and the second device based on the load states.
 14. The method asrecited in claim 13, wherein establishing the communication channelbetween the first device and the second device comprises determining acode pattern based on tuning and detuning between the first device andthe second device.
 15. A computing device, comprising: a processor; anda memory storing instructions that when executed by the processor causethe computing device to perform steps that include: coupling a firstelectromagnetic field of the computing device to a first device;coupling a second electromagnetic field of the computing device to asecond device, wherein the first device is communicatively coupled tothe second device; receiving load states from the first device and thesecond device; wirelessly distributing power to the first device and thesecond device in accordance with the load states, wherein at least aportion of the power received by the first device is wirelessly providedto the second device; receiving an indication that a power transferefficiency has dropped below a threshold for at least the first deviceor the second device; and when an updated load state is communicatedbetween the first device and the second device: causing a wirelessredistribution of the power between the first device and the seconddevice based on the updated load state.
 16. The computing device asrecited in claim 15, wherein the steps further include: establishing acommunication channel between the first device and the second devicebased on the load states.
 17. The computing device as recited in claim16, wherein establishing the communication channel between the firstdevice and the second device comprises determining a code pattern basedon tuning and detuning between resonant circuits of the first device andthe second device.
 18. An apparatus, comprising: a resonant circuit; aprocessor; and a memory storing instructions that when executed by theprocessor cause the apparatus to perform steps that include: coupling afirst electromagnetic field of a first device and the apparatus;communicatively coupling to a second device, wherein the second deviceis coupled to the first device via a second electromagnetic field;providing a load state to the first device; receiving, based on the loadstate, wireless power from the first device; providing wireless power tothe second device; providing feedback to the first device indicatingthat a power transfer efficiency has dropped below a threshold; and whenan updated load state is received from the second device: causing awireless redistribution of the power between the apparatus and thesecond device based on the updated load state.
 19. The apparatus asrecited in claim 18, wherein the steps include: establishing acommunication channel between the apparatus and the second device bydetermining a code pattern, wherein the code pattern is based on tuningand detuning between resonant circuits of the apparatus and the seconddevice.
 20. The apparatus as recited in claim 9, wherein the stepsfurther include: causing the resonant circuit of the apparatus to tuneand detune to at least one of multiple frequency bands of the firstdevice.